Piezoelectric Ba and Ti co-doped BiFeO textured films: selective growth of solid solutions or nanocomposites

Metal organic chemical vapor deposition (MOCVD) is exploited as a synthetic route to produce Ba and Ti co-doped BiFeO 3 thin films. A facile approach based on a molten multi-component source, consisting of a Bi(phenyl) 3 , Fe(tmhd) 3 , Ba(hfa) 2 ·tetraglyme and Ti(tmhd) 2 (O-iPr) 2 (phenyl = -C 6 H 5 , H-tmhd = 2,2,6,6-tetramethyl-3,5-heptandione; O-iPr = iso-propoxide; H-hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; tetraglyme = CH 3 O(CH 2 CH 2 O) 4 CH 3 ) mixture, is applied for the MOCVD based fabrication of doped BiFeO 3 films on SrTiO 3 :Nb(100) substrates. The applied characterization techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM), provide a suitable correlation between processing parameters/precursor mixtures and the nature of the deposited films, in terms of the formation of solid solutions of the type Bi (1− x ) Ba x Fe (1− y ) Ti y O 3 vs. the formation of Bi (1− x ) Ba x FeO 3 /Bi (1− x ) Ba x Fe (1− y ) Ti y O 3 nanocomposite films. Piezoresponse force microscopy (PFM) is applied to correlate the nanostructure/composition and piezoelectric/ferroelectric properties. Accurate control of the MOCVD process parameters results selectively and reproducibly in the formation of two different systems: a single-phase solid solution film and a nanocomposite sample formed by nanocolumns embedded in a solid solution film.